Here is the full list of all 9 Cat Quest II achievements. It takes around 12-15 hours to unlock all of the achievements on Windows.
Completed the Main Quest!
Reached level 99!
Obtained all 12 spells!
Unlocked 3 Royal Arts!
Entered the new continent!
Completed the first quest!
Cleared all 73 dungeons!
Completed all 67 side quests!
Obtained all 101 equipment!